1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine and a printer, and more particularly, to an image forming apparatus characterized by a technique of performing registration of an image to be formed, with a sheet being conveyed.
2. Description of the Related Art
There has been proposed a technique for an image forming apparatus in which, prior to an image being transferred to a sheet, a registration patch is formed on a photosensitive member, between sheets, and performing registration of the image with the sheet at a timing of detecting the registration patch as a reference (for example, see Japanese Laid-Open Patent Publication (Kokai) No. 11-194561).
There has also been proposed a technique of correcting the timing of registration by a patch in order to follow change in the perimeter of an intermediate transfer member and the like (for example, see Japanese Laid-Open Patent Publication (Kokai) No. 2001-215857).
There has also been proposed a technique of, in a case where there is a scratch or the like on the photosensitive member or the intermediate transfer member at a position of the registration patch being formed, invalidating the image or moving the image position.
As described above, in a conventional image forming apparatus, if an image is invalidated in a case where there is a scratch or the like on a photosensitive member or an intermediate transfer member at a position of a registration patch being formed, the used developing solution is wasted, and furthermore, a cleaning member is deteriorated and the productivity is lowered. In the case of moving the image position also, the lowering of the productivity cannot be avoided.